Method and apparatus for recording and reproducing sound



Jan. 30, 1940. LQHN 2,188,687.

METHOD AND APPARATUS FOR zmconnme AND REPRODUCING sounb Filed Apr i l 7, 1938 2 Sheets-Sheet 1 V lNVENTO R. .PETEI? A ATTORNEYS -P. LDHN METHOD AND AIIIPARATUS F03 RECORDING AND anrnonucme scum) Filed 4 \pril '7, 195a 2 Sheets-Sheet 2 INVENTOR. 7 575,? 0///\/ ATTORNEYS Patented Jan. 30, 1940 UNITED STATES PAT NT OFFICE DIETHOD AND APPARATUS FOR RECORDING AND REPRODUOING SOUND Peter Lohn, New York, N. Y., assignor of thirtyfour per cent to Ferdinand Savignano, New

York, N. Y. 1 Application April 1, .1938, Serial No. 200,640

' 3 Claims. (01. I'm-100.4)

This invention relates to improvements in sound recording and reproducing and more particularly to a method and apparatus for the recordation and reproduction of a sound record on a film, or like recording medium, to be used in motionpicture cameras and projectors.

An'object of the invention is to simplify the recordatlon and reproduction of a sound record and to provide a practical apparatus for attain- 19 ing this end which will be comparatively inexpensive, and make the invention applicable for home use.

- Anotherobject is to record sound upon a strip, such as a motion picture film, by bringing the latter into association with cooperating members one of which imparts vibrations to the strip and the other cuts a record trace therein, and by softening the surface of the strip in which the trace is formed concurrently with the cutting operation.

A further object is toelectrically reproduce sound waves by the utilization of a light sensitive element which is responsive to variations in a light beam occasioned by the passage of said beanr through a mechanically formed record trace in a film.

The above and other objects will appear more clearly from .the following detailed description when taken in connection withthe accompanying drawings which illustrate preferred embodiments of the inventive idea.

In the drawings:

. Figure 1 is a side elevation, partly in section,

of one form of sound recording apparatus which may be mounted upon a moving picture camera. Figure 2 is a top plan view of said apparatus. Figure 3 is a fragmentary detailed sectional view illustrating the means for maintaining the film in cooperative relation to the element for forming the record trace therein.

Figure 4 is an enlarged fragmentary view showing the manner in which the sound record is cut in an edge of the film.

Figure 5 is an enlarged fragmentary plan view of a film showing a record trace cut thereinin accordance with the invention.

Figure 6 is a longitudinal section on the line 6-45 of Figure 5.

Figure '7 is a transverse section through the portion of the film containing the sound record.

Figure 8 is a fragmentary elevation, partly in section, of another form of recording mechanism.

Figure 9 is a detail elevation of. the cutter used with the mechanism of Figure 8.

Figure 10 is a longitudinal section through a part of a record trace formed in a film by the mechanism of Figure 8, and,

Figure 11 is a diagrammatic view illustrating the manner in which electrical reproduction of the mechanically formed sound record of Figs. 6 or 10 may be accomplished.

In the use of the sound recording apparatus illustrated in the different forms of the invention, a standard photographic film l2 of the sixteen millimeter type may be employed, consisting of superimposed layers of Celluloid and sensitized emulsion and, in accordance with the present invention, the record trace I3 is cut in the Celluloid surface of the film in the space between the picture frames l4 and one edge of the film, as best illustrated in Fig. 5.

The recording apparatus shown in Figs. 1 to 4 comprises a frame, generally indicated by the numeral l5 which, if desired, may be mounted directly upon a moving picture camera or connected thereto in such a way that the film I2 is fed to the recording apparatus in an unexposed condition for the recordatlon of the sound record thereon after which it is fed back to the camera for picture 'exposure. The recording mechanism, which is supported by the frame l5, may be operated from the camera by a flexible transmission l6 extending about a pulley I'I carried by one end of the shaft l8 of said mechanism. Said shaft also carries a worm gear l9 meshing with the worm of the toothed wheel the teeth of which engage in the apertures 2| f of the. film l2 so as to feed the same around the pulleys 22 in the direction of the arrows and past the recording mechanism that operates to form the record trace 13 in the film synchronously with the taking of pictures by the operation of the camera.

The shaft I8 is also utilized to drive the recording mechanism by means of a pulley 23 mounted on said shaft and a flexible endless element 24 engageable with said pulley and also a pulley 25 carried by one end of the shaft. 26 supported intermediate its end by a bearing 21 mounted upon the frame. l5. Said shaft 26 extends through a housing 28 supported upon two spaced lateral extensions 29 at the upper end of the frame I5, and so arranged on said extensions as to bridge the space between the same. Mounted upon the portion of the shaft 26 disposed within the housing 28 is a cutting element 30 in the form of a disc, the major portion of which is enclosed within the housing and which has its periphery projecting therefrom and sharpened to a knife edge for contact with the Celluloid sur- T 26, the plane of .said cutter is arranged perpenface of the film l2 as the latter passes beneath the cutter. In disposing the cutter on the shaft dicularly to the surface of' the film in which the record trace I3 is formed by the rotation of the cutter and passage of the film therebeneathj varying characteristics of said trace, as illustrated in Figs. 6 and 7, which are subsequently translated into sound by a reproducing mechanism, are effected by vibrations imparted to the film in accordance with sound waves transmitted to a conventional sound pick-up device 3| mounted upon the frame I 5 and having a vibratory stylus 32 engageable with the under surface of the film in opposed relation to the edge of the cutter 30. In order to properly guide the. film past the cutter 30 and stylus 32 there are provided two film gates 33 hingedly supported upon the frame IS in association with the two extensions 29, the inner adjacent ends of said gates being spaced to leave free for vibration under the influence of the stylus 32 a. portion of the film contiguous to the cutter 30. Each of the gates 33 has a spring latch 34 for engagement with the free edge of its associated element 29, and said gate carries a spring pressed shoe 35 which engages the under surface of the 'film to retain the same in a track 36 secured to the under surface of said extension 29.

In order to facilitate the formation of the record trace E3 in the film, it is desirable to soften the Celluloid portion thereof in which the record is out, simultaneously with the cutting operation. To this end, provision is made in 'the housing 28 for containing heating elements 31, preferably in the form of coils, disposed on opposite sides. of the cutter 30 and connected through conductors 38 to a suitable source of current. In this manner the cutter 30 is heated by the coils 31 and, through conduction, this heat is transmitted to the periphery of the.cutter where it engages the film to heat and thus soften the same at the instant the film is beingcut. Through such arrangement, the film is heated only for a time sufliclent to facilitate the formation of the trace therein and this permits the film to immediately cool off after the cutting operation so that a minimum of time will elapse'during which the mm is actually heated.

In the form of recording apparatus shown in Figs. 8 and 9, the film I2 is fed through the gates 33in the same manner as previously described except that, in this instance, the position of the film is'reversed so that its Celluloid surface in which the record trace is formed, is uppermost. On one of the extensions 29 of the frame l5, there is mounted, by means of a bracket 39, a sound pick-up device 40 having a vibratory stylus 4| which is preferably disposed at an angle of about degrees to a surface of the film in which the record trace 42 (Fig. 10) is to be cut. The lower free end of the stylus 4| ispr qy ided with a head 43 in which is secured a'blade 44 having an arcuate cutting edge 45 for engagement with the upper surface of the film l2 in the space between the extensions 29 and gates 33 so'that as said stylus is vibrated by the diaphragm (not shown) of the device 40 the unsupported portion of the film l2 will be free to fiex slightly under the influence of the pressure stylus 4| extends.

of the cutter 44 thereagainst and at the nine time the record trace 42 will be cut into the film. Similar to the first embodiment described, the cutter blade 44 is heated to facilitate the formation of the record trace and, for this purpose,

a housing 46 is secured to-the same extension 29 of the frame I! upon which the device 49 is mounted, and is provided'with a central opening through which the intermediate portion of the The housing 49 encloses a heating coil 41 which encircles the stylus 4| and is supplied with current through the conductors 48 connected to a suitable source. 'Ihe heat thus supplied to the stylus 4| is transmitted, by conduction, to the cutting blade 44 and from thence.

to the surface of the film as said blade contacts the latter so that. said film is temporarily softened while the sound record is being formed therein.

In the productionof sound from the record traces l3 and 42 mechanically formed in the film in the manner above described, it has been found that an accurate and faithful reproductionmay be had by employing an electrical apparatus such as partially and schematically shown in Fig. 11. Said apparatus may include an exciter lamp 49. and a light sensitive element 50, such as a photo-electric cell, arranged to have the film I2, and more particularly that portion thereof containing the record trace, passed therebetween so that a beam of light 5| having its source at the lamp 49 and extending through a conventional optical system 52, will be directed upon the record trace as the film is fed between the elements 49, 50. As said beam is impinged upon the cuts forming the record trace, the angles of said cuts produce refraction of the light beam passing through the film and thus the luminosity of the light sensitive element 5| will be varied in accordance with the degrees of refraction and, in a manner well known in the art, such variations in translated into sound.

What is claimed is:

1. Sound recording apparatus comprising, in combination, a sound responsive device having a vibratory element engageable wlth-one surface of'a film to impart vibrations thereto in accordance with sound transmitted tosaid device, a cutter engaging the other surface of said film in opposed relation to said vibratory element,

, means to heat said cutter, means to feed said film past said element and cutter, and spaced film gates forming enclosed passageways for said film disposed on opposite sides of said element and cutter and through which said film is guided with the portion of the film in the space between said members unsupported so that it' will flex means within said housing to heat said cutter,-

means to feed said film past said element and cutter, and film gates supported by said frame said element 5. may be and each associated with'one of said extensions for guiding said film as it is fed to and beyond said cutter.

3. Sound recording apparatus comprising, in combination, a supporting frame having horizontally spaced lateral extensions, a sound responsive device having a vibratory element engageabie with one surface of a film to impart vibrations thereto, a housing supported by said extensions adjacent the space between the latter, a rotary cutter mounted in said housing and extending into said space and engaging the other surface of said film in opposed relation to said vibratory element, heating elements arranged in said housing on opposite sides of said cutter, means to feed said film past said vibratory element and cutter, and film gates pivoted to said supporting frame and cooperating with said extensions to support and guide said film in its movements.

PETER LOHN. 

